This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. An extracellular membrane protein failed to incorporate Se and other heavy atoms for structure determination. A strategy was developed to collect S data for structure determination (the S K-edge is at 5.015 A). Data were recorded at a wavelength of 2 A. A helium cold stream was incorporated to reduce background scatter. Highly redundant data were collected yielding a redundancy of 22 (3 positions on the crystal, 360 degrees of data each, 1080 degrees total) yielding an Rsym of 10% to 2.1 A resolution. Images were collected in an inverse beam mode using a wedge of 1 image (for every 0.5 deg. oscillation, phi was rotated 180 degrees). The data will be analyzed to establish the structure and the relevance of the method.